Is DOT4 Brake Fluid Universal?
1 Answers
Qualified brake fluids of the same quality grade can be mixed. If they are DOT4 brake fluids from reputable brands, they can be mixed. However, when switching from a lower-quality DOT3 brake fluid to a higher-quality DOT4 brake fluid, the original brake fluid must be completely drained. Brake fluids of different quality grades should not be mixed. Although the chemical properties, high-temperature, and low-temperature performance of brake fluids are compatible, there are slight differences in their formulations, which can cause minor chemical reactions when mixed. Therefore, mixing brake fluids can lead to unpredictable consequences, and it is strongly advised not to attempt it. Precautions for Replacing Brake Fluid: It is best to replace brake fluid at a 4S shop. There are two methods for replacing brake fluid: manual replacement and pressurized replacement using a brake fluid changer. Manual replacement is more common in small auto repair shops and typically requires two to three people to operate, with responsibilities divided into draining the old fluid, pressing the brake pedal, and adding new fluid. This method has two significant drawbacks: it is prone to air ingress, and the old fluid may not be completely drained. Determining When to Replace Brake Fluid: The first method is to follow the "maintenance manual" guidelines, which recommend replacement every 2 years or 40,000 kilometers, or when the fluid appears visibly cloudy. The second method involves using "professional testing equipment" to check the fluid. Replacement is necessary if the water content reaches 2.5% or the boiling point falls below 230°C.
